A particular problem encountered, however, in using such film forming latices for soil erosion control is the limit on the useful life of the deposited film caused by the tendency of the film to deteriorate upon weathering and leaching of hydrophilic components which break the continuity of the film and destroy the ability of the film to hold the surface soil particles together. We have found that the useful life of such films and their ability to bond the surface soil particles can be increased, such that one application will last as long as four months without maintenance, by adding to a latex a resinate compound and enzymes in an aqueous composition.
As is well known in this art (see U.S. Pat. No. 2,961,799) the latex should form a water-insoluble rubbery film and, hence, almost any elastomer-forming polymer can be used. Thus, for example, natural rubber latex, reclaimed rubber latex, latices of synthetic materials such as polyisoprene, nitrile rubber, polysulphide, silicone rubber, polyester rubber and the like have been suggested. We have found, however, from the standpoint of the film produced, best results are obtained utilizing latices of butadience-styrene copolymer, butyl rubber and neoprene. Generally, in usage, the latex composition should be diluted with water to reduce the polymer solids content to about 10 to 30 parts per thousand for best results in application to the soil using conventional spraying equipment. Generally, the amount of polymer required for permeable films is on the order of 150 pounds per acre, while non-permeable films can be obtained on the order of 500 pounds of polymer per acre.
There are four primary categories of enzymes. 1. Protease 2. Lysase 3. Amylase and 4. Cellulase. Protease and Amylase enzymes work well together and are commonly formulated in detergent compositions for removal of soil. For enzymes to provide a zymalytic reaction, they must function at a pH of about 6.0 to 8.5 and in a composition containing less than 50% water.
U.S. Pat. No. 3,174,942 to Erikson discloses a soil erosion control composition which contains a diene latex in combination with bentonite. The compositions produce a rubbery, continuous and porous film which is bonded to the surface soil particles.
U.S. Pat. No. 4,592,931 to Cargle, which is herein incorporated by reference, discloses a method of treating soil to enhance its geotechnical properties with a composition containing homopolymers and copolymers of acrylic acid which can be used in the present invention.